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[BUG/PRB.] VFP 9.0 FIX - INVALID RELATIONALEXPR EXPRESSION
January 2024
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CCB
1. BUG:
In vfp9 (and vfp6, vfp7, vfp8), if the RelationalExpr expression includes the EVALUATE() or TYPE() functions, vfp will crash.
1, If the RelationalExpr expression includes the macro substitution,
vfp will cause the error "Relational expression is not valid (Error 1555)".
*PROC testrelationalexpr_macro
SET STEP OFF
SET ECHO OFF
SET DEBUG OFF
SET ESCAPE OFF
SET TALK OFF
SET SAFETY OFF
_SCREEN.VISIBLE=.T.
_SCREEN.WINDOWSTATE=2
SET EXCLUSIVE OFF
SET MULTILOCK ON
SET COLLATE TO "MACHINE"
CLOSE DATABASES ALL
CLOSE TABLES ALL
PUBLIC x1
x1="CHR(65)"
DO FORM testrelationalexpr_macro.scx
CLOSE DATABASES ALL
CLOSE TABLES ALL
RETURN
* END OF PROC TESTRELATIONALEXPR_MACRO.
In the testrelationalexpr_macro.scx:
relation1.RelationalExpr = "fld1+LEFT(&x1,0)"
2, If the RelationalExpr expression includes the EVALUATE() or TYPE() functions, vfp will crash.
*PROC testrelationalexpr_evaluate
SET STEP OFF
SET ECHO OFF
SET DEBUG OFF
SET ESCAPE OFF
SET TALK OFF
SET SAFETY OFF
_SCREEN.VISIBLE=.T.
_SCREEN.WINDOWSTATE=2
SET EXCLUSIVE OFF
SET MULTILOCK ON
SET COLLATE TO "MACHINE"
CLOSE DATABASES ALL
CLOSE TABLES ALL
DO FORM testrelationalexpr_evaluate.scx
CLOSE DATABASES ALL
CLOSE TABLES ALL
RETURN
* END OF PROC TESTRELATIONALEXPR_evaluate.
In the testrelationalexpr_evaluate.scx:
relation1.RelationalExpr = "fld1+EVALUATE('LEFT(CHR(65),0)')"
3, If the RelationalExpr expression includes the user-defined function and the user-defined function
includes EVALUATE() or TYPE() functions, vfp will crash too.
*PROC testrelationalexpr_udf_evaluate
SET STEP OFF
SET ECHO OFF
SET DEBUG OFF
SET ESCAPE OFF
SET TALK OFF
SET SAFETY OFF
_SCREEN.VISIBLE=.T.
_SCREEN.WINDOWSTATE=2
SET EXCLUSIVE OFF
SET MULTILOCK ON
SET COLLATE TO "MACHINE"
CLOSE DATABASES ALL
CLOSE TABLES ALL
DO FORM testrelationalexpr_udf_evaluate.scx
CLOSE DATABASES ALL
CLOSE TABLES ALL
RETURN
FUNCTION testrelationalexpr_udf_evaluate2
PRIVATE x2
x2=EVALUATE('LEFT(CHR(65),0)')
RETU ""
* END OF FUNCTION TESTRELATIONALEXPR_UDF_EVALUATE2.
* END OF PROC TESTRELATIONALEXPR_UDF_EVALUATE.
In the testrelationalexpr_udf_evaluate.scx:
relation1.RelationalExpr = "fld1+testrelationalexpr_udf_evaluate2()"
4, If the RelationalExpr expression includes the user-defined function and the user-defined function
does not include the EVALUATE() and TYPE() functions, vfp will run correctly.
5, If we don't set RelationalExpr expression at design-time, we can set RelationalExpr expression at run time.
For example,
THISFORM.DATAENVIRONMENT.ADDOBJECT("Relation1","Relation")
THISFORM.DATAENVIRONMENT.relation1.PARENTALIAS = "testa"
THISFORM.DATAENVIRONMENT.relation1.RELATIONALEXPR = "fld1+EVALUATE('LEFT(CHR(65),0)')"
THISFORM.DATAENVIRONMENT.relation1.CHILDALIAS = "testb"
THISFORM.DATAENVIRONMENT.relation1.CHILDORDER = "fld1"
vfp will not crash, BUT vfp will run incorrectly:
now the RELATION(1) is not equal to "fld1+EVALUATE('LEFT(CHR(65),0)')",
it is equal to "LEFT(CHR(65),0)" (the parameter passed to the EVALUATE() or TYPE() functions).
6, If we don't use the relation object, we can use SET RELATION TO statement instead of the relation object,
then there is no any problem.
2. CAUSE:
There are some BUGs in the following code.
3. RESOLUTION:
We can write some code to fix the BUG.
Label722b1b ::
mov ecx , dword ptr [ Data937f94 ] ;0x00722b1b : 8b0d947f9300
pushd 00h ;0x00722b21 : 6a00
lea edx , dword ptr [ esp + 02124h ] ;0x00722b23 : 8d942424210000
push edx ;0x00722b2a : 52
call Fun434500 ;0x00722b2b : e8d019d1ff
test eax , eax ;0x00722b30 : 85c0
jle Label722b59 ;0x00722b32 : 7e25
pushd 00h ;0x00722b34 : 6a00
pushd 01h ;0x00722b36 : 6a01
pushd 00h ;0x00722b38 : 6a00
lea eax , dword ptr [ esp + 0212Ch ] ;0x00722b3a : 8d84242c210000
push eax ;0x00722b41 : 50
call Fun430428 ;0x00722b42 : e8e1d8d0ff
test eax , eax ;0x00722b47 : 85c0
jne Label722b59 ;0x00722b49 : 750e
;
; -------------------------------------------------------
; VFP 9.0 FIX - INVALID RELATIONALEXPR EXPRESSION
; January 2018
; -------------------------------------------------------
; CCB
;
; If the RelationalExpr expression includes the EVALUATE() or TYPE() functions, vfp will crash.
;
; 2018/1/23, by ccb
;
mov dword ptr vfpa_relationalexpr_flag,01h
mov eax,dword ptr [ Data937f94 ]
cmp byte ptr [eax],0FDh
je Label722b4a
Label722b49 ::
call Fun4360e0
cmp byte ptr [eax],0FDh
jne Label722b49
Label722b4a ::
sub eax,dword ptr [ Data937f94 ]
inc eax
mov dword ptr vfpa_relationalexpr_len,eax
cmp dword ptr vfpa_relationalexpr_len,100h
jae Label722b4b
push ecx
push esi
push edi
mov ecx,dword ptr vfpa_relationalexpr_len
mov esi,dword ptr [ Data937f94 ]
lea edi,dword ptr vfpa_relationalexpr_data
cld
rep movsb
pop edi
pop esi
pop ecx
Label722b4b ::
mov eax , dword ptr [ Data937f94 ] ;0x00722b4b : a1947f9300
push esi ;0x00722b50 : 56
push ebx ;0x00722b51 : 53
call Fun44df4c ;0x00722b52 : e8f5b3d2ff
;
; -------------------------------------------------------
; VFP 9.0 FIX - INVALID RELATIONALEXPR EXPRESSION
; January 2018
; -------------------------------------------------------
; CCB
;
; If the RelationalExpr expression includes the EVALUATE() or TYPE() functions, vfp will crash.
;
; 2018/1/23, by ccb
;
mov dword ptr vfpa_relationalexpr_flag,00h
jmp Label722b63 ;0x00722b57 : eb0a
We can also use the EXECSCRIPT() function instead of the EVALUATE() function,
and use the VARTYPE() function instead of the TYPE() function, and then vfp will run correctly.
For example,
RelationalExpr = "fld1+EVALUATE('LEFT(CHR(65),0)')"
we can change it to:
RelationalExpr = "fld1+EXECSCRIPT('RETURN '+'LEFT(CHR(65),0)')"
VFP C++ Compiler frequently uses the _Evaluate() and _Execute() API functions,
so if the RelationalExpr expression includes the user-defined function,
recommend to set VFP C++ Compiler does not compile the user-defined function.
For example, we can change it to:
FUNCTION testrelationalexpr_udf_evaluate2
=[FOXRUN OFF]
PRIVATE x2
x2=EVALUATE('LEFT(CHR(65),0)')
RETU ""
=[FOXRUN ON]
* END OF FUNCTION TESTRELATIONALEXPR_UDF_EVALUATE2.
4. APPLIES TO:
VFP 6.0.8167.0
VFP 6.0.8961.0 (SP5)
VFP 7.0.0.9262
VFP 7.0.0.9465 (SP1)
VFP 8.0.0.2521
VFP 8.0.0.3117 (SP1)
VFP 9.0.0.2412
VFP 9.0.0.3504 (SP1)
VFP 9.0.0.4611 (SP2)
VFP 9.0.0.5015 (SP2)
VFP 9.0.0.5411 (SP2)
VFP 9.0.0.5721 (SP2)
VFP 9.0.0.5815 (SP2)
VFP 9.0.0.6303 (SP2)
VFP 9.0.0.6602 (SP2)
VFP 9.0.0.7423 (SP2)
The bug has been fixed in VFP Advanced.
5. REFERENCE WEBSITES:
1, baiyujia.com:
http://www.baiyujia.com
6. OTHER:
For reference only, there is no guarantees.
Any questions or suggestions, please send me an email at ccb2000@163.com.
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